• 대한전자공학회논문지SD
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• 제41권11호
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• pp.69-77
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• 2004

본 논문에서는 ground bounce 영향과 지연고장 검출을 함께 고려한 효율적인 보드레벨 연결선 테스트 생성 알고리즘을 제안한다. 제안된 알고리즘은 IEEE 1149.1의 연결선 테스트, ground bounce 영향에 의한 바운더리 스캔의 오동작 방지, 그리고 연결선의 지연고장 검출 능력을 포함한다. 본 논문에서 제안하는 기법은 기존의 기법에 비해 연결선의 지연고장 검출능력을 새롭게 추가하였지만, 연결선 테스트에 필요한 총 테스트 패턴 수는 기존의 기법과 비교해서 큰 차이를 보이지 않음을 실험결과에서 확인할 수 있다.

• 한국전산유체공학회지
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• 제15권4호
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• pp.53-59
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• 2010

Preliminary design of a ground plate, a device installed close to the aircraft model for wind tunnel test to simulate the ground effect, was performed by a numerical simulation. A two-dimensional numerical study was performed initially to decide the optimal leading edge and flap configurations. Then, three-dimensional studies were conducted to decide the optimal flap deflection angle for pressure distribution reduction since the plate and the plate supporting system generate static pressure difference between the upper and lower flow regions. Three-dimensional simulation additionally studied the effect of the clearance between the plate and the wind tunnel side wall. For the efficiency of computation, half model was simulated and a symmetric boundary condition was applied on the center plane. Based on the preliminary design, a ground plate was designed, manufactured and tested at the Korea Aerospace Research Institute(KARI) wind tunnel. The measured pressure differences versus flap deflection angle agreed well with the predicted results.

• 한국지진공학회논문집
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• 제27권2호
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• pp.111-118
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• 2023

The 2017 Pohang earthquake afflicted more significant economic losses than the 2016 Gyeongju earthquake, even if these earthquakes had a similar moment magnitude. This phenomenon could be due to local site conditions that amplify ground motions. Local site effects could be estimated from methods using the horizontal-to-vertical spectral ratio, standard spectral ratio, and the generalized inversion technique. Since the generalized inversion method could estimate the site effect effectively, this study modeled the site effects in the Korean peninsula using the generalized inversion technique and the Fourier amplitude spectrum of ground motions. To validate the method, the site effects estimated for seismic stations were tested using recorded ground motions, and a ground motion prediction equation was developed without considering site effects.

• 한국지반신소재학회논문집
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• 제17권2호
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• pp.1-7
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• 2018

해안지대나 습지와 같은 연약지반에 도로나 철도 건설이 빈번해지면서 이를 위한 연약지반 개량 사례가 증가하고 있다. 일반적으로 연약지반 개량시 작업조건만을 고려하거나 경제성만을 고려한 공법은 다수 존재하나 작업조건과 경제성을 함께 고려할 경우 적용 가능한 공법은 제한적이다. 이러한 경우 표층부와 심층부를 병용하여 개량하는 공법이 적용되어지는데, 이에 대한 기초적인 연구가 부족한 현실이다. 따라서, 본 연구에서는 연약지반에서 표층부 개량과 심층부 개량을 병용하는 경우에 대해 모형시험을 수행하여 지오그리드 보강 효과를 확인하고자 하였으며, 이때 표층부의 두께, 심층부 개량체의 직경 및 길이가 지오그리드 보강 효과에 미치는 영향을 파악하고자 하였다. 그 결과 표층부의 두께가 심층부의 직경보다 보강효과가 크다는 것을 확인하였고, 또한 표층부를 지오그리드로 보강한 경우 표층부의 강도가 증진되어 침하량이 저감됨을 확인하였다.

• 터널과지하공간
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• 제11권4호
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• pp.339-343
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• 2001

쉴드 터널과 같이 토사 지반 혹은 연암 지역에 건설되는 원형 단면을 가진 터널은 지진 시에 지반의 전단변형의 영향을 받아 좌우교차로 경사진 타원형상의 변형을 반복한다. 본 논문에서는 이 진동모드를 이용하여 지반-터널계의 상호작용에 관하여 검토하였다. 터널주변지반은 균질한 탄성체로 가정되었고 지반-터널라이닝 경계가 완전히 부착되어 있는 경우에 대한 상호작용효과를 검토하였다. 지반의 포아송비 및 강성이 증가할수록 지반으로부터 터널라이닝에 전달되는 변형률이 증가함을 확인할 수 있었다.

• Structural Engineering and Mechanics
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• 제43권6호
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• pp.835-845
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• 2012

This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

• 설비공학논문집
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• 제23권5호
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• pp.321-326
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• 2011

Recently, ground source heat pump (GSHP) systems have been introduced in many modem buildings which use the annually stable characteristic of underground temperature as one of the renewable energy uses. However, all of GSHP systems cannot achieve high level of energy efficiency and energy-saving, because their performance significantly depends on thermal properties of soil, the condition of groundwater, building loads, etc. In this research, the effect of thermal properties of soil on the performance of GSHP systems has been estimated by a numerical simulation which is coupled with ground heat and water transfer model, ground heat exchanger model and surface heat balance model. The thermal conductivity of soil, the type of soil and the velocity of groundwater flow were used as the calculation parameter in the simulation. A numerical model with a ground heat exchanger was used in the calculation and, their effect on the system performance was estimated through the sensitivity analysis with the developed simulation tool. In the result of simulation, it founds that the faster groundwater flow and the higher heat conductivity the ground has, the more heat exchange rate the system in the site can achieve.

• Structural Engineering and Mechanics
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• 제33권4호
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• pp.407-428
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• 2009

The effects of the uniform and spatially varying ground motions on the stochastic response of fluid-structure interaction system during an earthquake are investigated by using the displacement based fluid finite elements in this paper. For this purpose, variable-number-nodes two-dimensional fluid finite elements based on the Lagrangian approach is programmed in FORTRAN language and incorporated into a general-purpose computer program SVEM, which is used for stochastic dynamic analysis of solid systems under spatially varying earthquake ground motion. The spatially varying earthquake ground motion model includes wave-passage, incoherence and site-response effects. The effect of the wave-passage is considered by using various wave velocities. The incoherence effect is examined by considering the Harichandran-Vanmarcke and Luco-Wong coherency models. Homogeneous medium and firm soil types are selected for considering the site-response effect where the foundation supports are constructed. A concrete gravity dam is selected for numerical example. The S16E component recorded at Pacoima dam during the San Fernando Earthquake in 1971 is used as a ground motion. Three different analysis cases are considered for spatially varying ground motion. Displacements, stresses and hydrodynamic pressures occurring on the upstream face of the dam are calculated for each case and compare with those of uniform ground motion. It is concluded that spatially varying earthquake ground motions have important effects on the stochastic response of fluid-structure interaction systems.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 봄 학술발표회 논문집
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• pp.365-372
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• 1998

• 터널과지하공간
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• 제19권5호
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• pp.388-396
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• 2009

록볼트는 지하공동 굴착시 암반의 과도한 이완을 초기에 방지할 수 있는 가장 중요한 터널 지보재 중 하나이다. 국내외에서 록볼트의 설치에 따른 침하저감 및 보강효과, 다양한 록볼트 형태에 따른 터널 안정성 증대효과 등 록볼트 지보효과에 대한 많은 연구는 있으나, 록볼트에 긴장력을 가함으로써 절리암반의 지반보강 효과에 대한 연구는 미흡한 실정이다. 본 연구에서는 수평절리암반을 모사한 모형지반에서 록볼트의 긴장력 및 설치간격을 변수로 하여 대형모형실험을 실시하여, 록볼트에 의한 지반 보강효과를 확인하였다. 록볼트의 긴장력에 의한 절리암반 보강효과를 확인하기 위하여 단순보를 조성하여 긴장력과 설치간격을 변수로 하였다. 굴착에 따른 모형지반 중앙하부 처짐량을 측정하여 록볼트로 보강된 보강영역의 지반변형계수를 도출하였다.